TNF and Sepsis: Preclinical models of sepsis can be classified into three categories based on the mechanism involved, including administration of a cytokine or toxin [e.g., tumor necrosis factor (TNF) or lipopolysaccharide (LPS)], administration of a viable pathogen (e.g., E. coli), or disruption in the animal's protective barrier allowing for bacterial invasion [e.g., cecal ligation and puncture (CLP)] (9).